Hi Sergio, I used 3/8 inch length and a flat washer (about 3/4" diameter as I recall). Unless you seal it very well, this cover will leak at the lower rear and mimic a rear main seal leak. Anytime I have to remove one, I straighten the area around the bolt holes really well. The flat washer keeps the bolt head from deforming the cover. Good luck.


~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end